An advertisement posted this month on a YouTube account that promotes WeChat in South Africa makes fun of Facebook founder Mark Zuckerberg, suggesting that if he wants to make real friends, he’d be better off using WeChat, a rival mobile messaging program owned by Chinese Internet conglomerate Tencent Holdings. The 35-second ad was also posted on a Facebook page that has been continuously posting ads for WeChat since it was launched at the end of 2012.

In the commercial, a character named Mark, sporting tousled curly hair that looks an awful lot like Zuckerberg’s, whines to a therapist, saying “I mean, I invented the social network, and now my friends, they’re unfriending me.”

In a German-accented response, the therapist tells Mark to use WeChat’s location-based friend radar function, which he says will help him find “real friends.” Unconsoled, Mark responds to this advice by breaking into tears, prompting the therapist to respond, “Ah, come on, Mark, don’t make me unfriend you too.”

Launched in early 2011,WeChat currently has 355 million monthly active users, mostly in China. In South Africa, it’s locked in a battle for market domination with WhatsApp, the messaging app Facebook bought in February for $19 billion.

In a second video also posted to the site, the same German therapist is confronted by lawyers sent by “Mark,” who’ve apparently been dispatched to stop him from prescribing WeChat to help his patients. “Oh Mark, your anger is merely a cry for help,” the therapist replies. “Don’t worry,” he says. “With WeChat animated stickers, you can find a way to express your emotions.

Last year Tencent said it would spend as much as $200 million to promote WeChat outside China, and this year, the company signaled that it will continue to spend to market WeChat. Tencent once tried to acquire WhatsApp, according to people familiar with the matter, but the venture failed.

In South Africa, WeChat continues to trail WhatsApp, ranking as the sixth and eighth most popular apps on iPhone and Android phones, respectively, compared to WhatsApp, which tops both lists, according to research firm App Annie’s mobile app tracker

An ad targeting Mr. Zuckerberg could help users distinguish between the two apps, which in the past have been confused by users. According to Arthur Goldstuck, managing director of South African technology research company World Wide Worx, when WeChat launched in South Africa in February 2013, many potential users got confused and accidentally downloaded rival WhatsApp instead.

“Our understanding is that WhatsApp downloads grew by 50% in the two months after WeChat was launched here…indicating that there is confusion between the two,” Mr. Goldstuck said.

In an interview last year, Brett Loubser, who heads WeChat’s marketing in South Africa, said that he’d heard about users being confused about the difference between WhatsApp and WeChat. “It’s an extremely competitive environment,” he said. “Obviously the dream is to be number one.”

Asked to comment, Tencent said Thursday it was investigating whether the ad was in fact theirs.

Take-no-prisoner efforts to build market share are normal in China’s Internet sector. Chief executives bicker publicly on social media, and companies run smear campaigns against each other, reaching levels of public antagonism less common outside of China.

Thus far, Chinese companies like Tencent have been taking a quiet, under-the-radar approach to investing outside China. But if the tone of these ads are any indication, their marketing, at least, might be starting to get more rancorous.